Geology Reference
In-Depth Information
values of 0.831-0.999
impart in these equations the necessary robustness and
enable recommending them for the application in engineering forecasting.
8.3
Quantitative Correlation Between Hydrocarbon
Saturation and Thermobaric Regime of Local
Structures
Clear functional correlation between thermobaric regime of the subsur-
face and ground water dynamics in the Alpine mobile belt basins was iden-
tified in Chapters 4 and 5. As shown above, hydrocarbon reserves in traps
are in direct correlation with the latter. It is therefore possible to determine
the presence, format and nature of the connection between quantitative
parameters of the hydrocarbon saturation (
М
,
Q
i
) and temperature and
baric parameters of the local highs.
The following pattern was identified when comparing the said parame-
ters with average values of geothermal gradients (Г) and formation pressure
abnormality factors (
К
ан
) for the fields in the South Caspian Depression
and other Alpine mobile belt regions (Tables 8.1-8.3, Figures 8.7-8.10)
(Rachinsky, 1987, 1989). Structures' oil and gas-saturation in all areas
increases with the growth in Г and
К
ан
to a certain limit. Any further
growth results in the decline of
М
and
Q
i
.
Numerical solution of
Q
i
=
f
(Г),
Q
i
=
f
(
К
ан
) equations using (Tables 8.9,
8.10) group argument counting technique
show rater high values of the
correlation ratios of between 0.829 and 0.995. It gives to the identified cor-
relations sufficient robustness for utilizing them in forecasting oil and gas-
saturation of local structures.
The unimodal correlation nature between thermobaric parameters and
oil and gas occurrences substantiates the presence, hence, the possibility
of the identification in each region of environments for the beginning and
incompleteness (continuation) of the formation, preservation and dis-
sipation of hydrocarbon aggregations. The first case in Figures 8.7-8.10
corresponds with the geometric locus in the area of maximum and ele-
vated temperature gradients and abnormality factors [tail branches of the
curves
М
=
f
(Г),
Q
i
=
f
(Г),
М
=
f
(
К
ан
),
Q
i
=
f
(
К
ан
): thermobarically-closed
structures with no or substantially restricted water-exchange limiting the
hydrocarbon influx]. The second case corresponds with near-maximum
area (optimal conditions for the oil and gas accumulation). The third case
corresponds with low and minimal gradient and abnormality factor val-
ues (left branches of the same curves). Those are thermobarically-open
